Many metal forming processes involve steps of heating a workpiece and applying a shaping force to it for the purpose of altering or maintaining a desired shape profile. Temperature control is generally quite important in such processes for the purpose of attaining or maintaining a desired metallurgical state and/or carrying out heat treatment steps such as nitriding, carburizing and the like. Resistance heating, wherein an electrical current is flowed through the workpiece so as to generate heat, is preferred in a number of metal forming processes since resistance heating is very quick and very controllable so that precise temperatures may be achieved and/or selected regions of a workpiece heated.
The prior art has implemented a number of metal forming processes in which resistance heating is combined with various shaping steps such as bending, die forming, stretching and the like. Some such systems are shown, for example, in U.S. Pat. Nos. 2,972,043; 5,737,954; 6,463,779; 6,384,388; 5,515,705; 3,933,020; 6,868,709; and 5,744,773.
In various metal working processes, it is necessary to contact a workpiece with a liquid or gaseous fluid during the course of a forming and treatment process. This fluid may comprise a quench fluid used to control the temperature of the workpiece, or it may comprise a treatment fluid such as a species which is chemically reactive with the metal of a workpiece; such treatment fluids may comprise nitriding fluids, carburizing fluids, and the like.
In those instances where the fluid is used to moderate or affect the properties of the finished article, it is very important that the fluid uniformly contact substantially all of the workpiece, so that its effect on all portions of the workpiece is equal. In this regard, it is notable that the systems and methods of the present invention are operative to deliver the fluid to substantially all of the length of the workpiece. In this regard, the system is configured and operative to deliver a flow of fluid through the interior of a hollow workpiece so as to contact substantially all of the length of the interior surface with the fluid. In the instance of a solid workpiece, the system is configured and operative to deliver a flow of the fluid along substantially all of the length of the exterior surface of the workpiece. And, in the instance of hollow workpieces, the system may operate to direct the fluid flow along substantially all of the length of the interior and exterior surfaces.
The system of the present invention is further configured so that, in particular embodiments, it includes an electrode clamp which engages the workpiece so as to deliver an electrical current thereto, while also functioning so as to direct the flow of fluid along substantially all of the length of the workpiece. The prior art, as represented by the U.S. Pat. No. 2,972,043, shows an electrode clamp which operates to engage a metal bar and deliver an electrical current thereto. The U.S. Pat. No. 2,972,043 recognizes the fact that the flow of electrical current can cause overheating of the workpiece in the region of the clamp, and therefore includes a spray nozzle for directing a flow of coolant fluid onto the clamp and associated portion of the workpiece. However, as shown, this nozzle is separate from the clamp, and even more importantly, it does not function to deliver the coolant fluid to substantially all of the length of the workpiece. In this regard, the stated object of the invention in the U.S. Pat. No. 2,972,043 is to limit the cooling to the surfaces of the workpiece which are engaged by the contacts. This is in contrast to the present invention which contacts substantially all of the length of the workpiece with a fluid.
The present invention is directed to a system which integrates heating, shaping, and fluid delivery functions into a single workpiece supporting station. The system of the present invention may be fabricated in modular form, and is amenable to being quickly reconfigured so as to allow for the manufacture of a variety of articles having different profiles and/or different metallurgical properties. As such, the system of the present invention is readily adaptable to high volume manufacturing processes. These and other advantages of the present invention will be explained with reference to the drawings, discussion and description hereinbelow.